664946651520 has 960 divisors, whose sum is σ = 2520648622800. Its totient is φ = 166824935424.

The previous prime is 664946651489. The next prime is 664946651527. The reversal of 664946651520 is 25156649466.

664946651520 is a `hidden beast` number, since 6 + 6 + 4 + 9 + 4 + 66 + 51 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664946651527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 8011405399 + ... + 8011405481.

Almost surely, 2^664946651520 is an apocalyptic number.

664946651520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664946651520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1260324311400).

664946651520 is an abundant number, since it is smaller than the sum of its proper divisors (1855701971280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664946651520 is an equidigital number, since it uses as much as digits as its factorization.

664946651520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289 (or 195 counting only the distinct ones).

The product of its (nonzero) digits is 9331200, while the sum is 54.

The spelling of 664946651520 in words is "six hundred sixty-four billion, nine hundred forty-six million, six hundred fifty-one thousand, five hundred twenty".